What is checked
ZIP central-directory bounds are validated. TAR header checksums are verified. TAR.GZ and GZIP expansion is bounded before inspection. The report flags encrypted ZIP entries, archive links and unsafe paths such as traversal names.
When inspection refuses a ZIP
For supported ZIP entries, MakeFileWork checks stored or deflated contents against CRC32, validates local headers, data descriptors and directory bounds, and rejects overlapping entries, duplicate names, undecodable filenames and local records missing from the central directory. Encrypted entries and unsupported encodings cannot be verified safely. Unsafe paths are flagged in the report rather than extracted.
ZIP links, special files and filename collisions
A ZIP entry can pass CRC32 and still be unsafe to extract. On Unix-origin ZIP files, the inspector reads the stored file-type bits to flag symbolic links, named pipes and other special entries. It also reports a directory entry that unexpectedly contains file bytes or whose declared type disagrees with its trailing slash. Names such as Report.txt and report.txt, or visually different Unicode names that normalize to the same path, are reported as collisions because common extraction destinations may overwrite one of them.
The report counts links, colliding paths and unsupported entry types separately; an integrity checksum only establishes that the archived bytes match their declared CRC, not that an entry is safe to open. The inspector does not follow links, create special files or extract ZIP contents. For your own files, create a new ZIP with ordinary files and unique names rather than renaming suspicious entries inside an untrusted archive.
Why a ZIP is not automatically a Word or Excel document
DOCX, XLSX and PPTX use ZIP containers. An archive that lists both Word and Excel document roots, or whose directory disagrees with its local headers, should not be relabeled as a verified Office document. The initial type detector routes these cases to ZIP inspection; the archive checker then evaluates supported entry integrity independently. For a document that fails to open, start with file diagnosis before choosing a repair workflow.
TAR.GZ is not the same as GZIP
A file named .tar.gz or .tgz must decompress to a structurally valid TAR archive. If it contains ordinary gzip-compressed text or a damaged TAR header, inspection rejects it without producing a misleading verified report. A single .gz file can legitimately contain non-TAR data.
Extension and signature must agree
A plain TAR renamed to .tar.gz is not a compressed archive, and gzip data renamed to .tar is not an uncompressed TAR. ZIP, TAR and GZIP extensions are checked against actual file signatures before any verified report is offered. Renaming a file does not convert its contents; choose the corresponding conversion tool instead.
Safety limits
Input is limited to 40 MB and expanded GZIP/TAR data to 100 MB. ZIP inspection supports up to 1,000 entries; TAR inspection applies the extraction limits of 200 regular files and 25 MB per entry, rejecting larger archives instead of reporting them as verified. Self-extracting ZIP stubs, unexplained gaps and unindexed local records are rejected rather than silently ignored. Inspection does not execute or open archived files.
Private by design
Inspection happens in your browser. The downloadable report contains filenames and structural metadata, not extracted file contents.
Example: why a ZIP may be rejected
A ZIP can contain reports/2026.csv and reports/../secret.csv. Even if both CRC32 values match, the second name could escape the expected folder when extracted. The inspector reports unsafe paths instead of unpacking them. Similarly, a ZIP with an unindexed local record is rejected: checking only the visible directory would hide content.
What to do after the report
Use Create ZIP to package your own clean files with unique names. If you have a TAR or TAR.GZ that passed inspection, use TAR/GZIP extraction to download its regular files as a new ZIP. CRC32 confirms accidental corruption checks, not whether files are trustworthy.